GENERAL KNOWLEDGE

Detailed explanation-1: -The planets Mercury, Venus, Earth, and Mars, are called terrestrial because they have a compact, rocky surface like Earth’s terra firma. The terrestrial planets are the four innermost planets in the solar system.

Detailed explanation-2: -Inner planets: the four closet to the sun. They are also called the “terrestrial planets” because they are made mostly of rock and metal. Outer planets: the four farthest from the sun. They are also called the “gas giants” because they are made mostly of gases.

Detailed explanation-3: -Terrestrial planets (Earth sized and smaller) are rocky worlds, composed of rock, silicate, water and/or carbon.

Detailed explanation-4: -The temperature of the early solar system explains why the inner planets are rocky and the outer ones are gaseous. As the gases coalesced to form a protosun, the temperature in the solar system rose. In the inner solar system temperatures were as high as 2000 K, while in the outer solar system it was as cool as 50 K.